Wave Transformation and Sand Transport on a Macrotidal Pocket Beach

Abstract

Available 17-day field data in Korea are analyzed to investigate the cross-shore wave transformation, currents and sand suspension in the intertidal zone, and beach profile changes of a macrotidal pocket beach with a gentle slope of 0.02 and tidal ranges of 4–7 m. The measured beach profile changes were less than 0.5 m despite the occurrence of two consecutive storms with significant wave heights exceeding 2 m. A cross-shore numerical model is shown to reproduce the gradual wave height decay in the migratory surf zone, the cross-shore current of the order of 0.1 m/s affected by flood and ebb tides, the suspended sand volume varying with the tidal cycle, and the small beach-profile changes. The computed cross-shore and longshore sand-transport volumes per unit width for the 17-day interval are relatively small, but extend the 400-m-wide cross-shore zone. The small volume and wide zone reduces the local erosion or accretion.